/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.bind.annotation;

import java.lang.annotation.*;

/**
 * Annotation which indicates that a method parameter should be bound to a
 * name-value pair within a path segment. Supported for {@link RequestMapping}
 * annotated handler methods in Servlet environments.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface MatrixVariable {

    /**
     * The name of the matrix variable.
     */
    String value() default "";

    /**
     * The name of the URI path variable where the matrix variable is located,
     * if necessary for disambiguation (e.g. a matrix variable with the same
     * name present in more than one path segment).
     */
    String pathVar() default ValueConstants.DEFAULT_NONE;

    /**
     * Whether the matrix variable is required.
     * <p>Default is {@code true}, leading to an exception thrown in case
     * of the variable missing in the request. Switch this to {@code false}
     * if you prefer a {@code null} in case of the variable missing.
     * <p>Alternatively, provide a {@link #defaultValue() defaultValue},
     * which implicitly sets this flag to {@code false}.
     */
    boolean required() default true;

    /**
     * The default value to use as a fallback. Supplying a default value implicitly
     * sets {@link #required()} to false.
     */
    String defaultValue() default ValueConstants.DEFAULT_NONE;

}
